Hydraulic valve lifter



1955 w. J. PURCHAS, JR 2,766,745

HYDRAULIC VALVE LIFTER Filed July 14, 1953 INVENTOR M7727; Jflmwimvz Wm Ag ATTO RN EY HYDRAULIC VALVE LIFTER William J. Purchas, Jr., Grand Rapids, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 14, 1953, Serial No. 367,890

Claims. (Cl. 12390) This invention relates to hydraulic valve lifters for antomatically taking up and adjusting the lash in the valve operating linkage of internal combustion engines and the like, and particularly to such devices in which oil serves as the hydraulic fluid and is continuously supplied from the engine lubricating system.

The conventional form of such lifters which is in most common use today comprises two slidably interfitted and correspondingly disposed cup-shaped members, defining an oil cushion or pressure chamber between their closed ends and a reservoir within the inner cup from which a one-way flow of oil is permitted into the pressure chamber through a check-valve controlled passage in the closed end of the inner cup. The oil trapped within the pressure chamber operates to transmit thrust between the cups, which thrust is in turn transmitted between the inner cup and the push rod or other valve actuating element by a third member which forms a closure for and is laterally supported by the open end of the inner cup. A certain amount of leak-down (i. e., escape of oil from the pressure chamber) is permitted to occur between the slidably interfitted surfaces of the inner and outer cups during each valve lifting stroke, resulting in a slight foreshortening of the over-all length of the lifter. This foreshortening is resiliently opposed by a spring urging the inner cup outwardly of the outer cup, and while the thrust load is relieved during the succeeding return stroke the suction created in the re-expanding pressure chamber induces oil flow thereinto from the reservoir to compensate for the leak-down during the previous lift stroke. Although in some lifter designs the leak-down oil is recirculated back into the reservoir through suitable passages provided for that purpose adjacent the open end of the inner cup, necessary leakage losses occurring in operation require in any event that the reservoir be constantly supplied with oil from the engine lubricating system either through registering side ports in the cup walls or through a passage in the closure member (depending on whether the lifter is designed for side feed or end feed).

While hydraulic litters of this design have proven highly satisfactory, the very close tolerances required in the fit of their sliding surfaces has adversely affected their cost of manufacture, and the tendency of those surfaces to accumulate varnish-like deposits which causes sticking of the parts in a manner to prevent seating of the engine valves has been a principal deterrent to their wider commercial adoption. It is the object of my invention to provide certain improvements in the design of such lifters which both reduce their cost and substantially eliminate this varnish sticking problem. I broadly achieve these results by so forming the internal surfaces of the outer cup and the upper (open end) external periphery of the inner cup that both the inner cup and its closure member have independent sliding engagement with the outer cup, and such deposits as may accumulate on any of the slidably interengaged surfaces of these members cannot interfere with the necessary fore- States Pate t O F ice shortening of the lifter to permit full seating of the engine valve in operation.

The means by which these and other advantages of my invention are obtained will be clearly understood from the following description of a preferred embodiment thereof, having reference to the drawing wherein:

Figure 1 is a cross sectional view of a portion of an internal combustion engine valve operating linkage including my improved valve lifter.

Figure 2 is an enlarged fragmentary view similar to Figure 1 and showing the parts of the valve litter in longitudinal section.

Figure 3 is a transverse sectional view taken substantially on line 3-3 of Figure 2.

The valve lifter designated generally by the numeral 1 is shown slidably mounted for longitudinal reciprocation in the lifter guide bore 2 formed in the engine cylinder block or crankcase 3 and has its lower end resting on the cam 4 whose shaft 6 is suitably journalled in the crankcase and driven in timed relation with the engine by conventional means, not shown. Longitudinal motion of the lifter is transmitted in the particular engine shown through a push rod 7 extending through the crankcase 3 and cylinder head 8 mounted thereon to a valve rocker 9 which is journalled for oscillation by a shaft 11 supported from the cylinder head by a pedestal 12. At 13 is shown an engine poppet valve controlling a port 14 communieating with the combustion chamber 16 at the upper end of an engine working cylinder 17 Which is slidably fitted with a piston 18. The stem 19 of the valve is slidably guided in a bushing 21 fitted in the cylinder head 8, and has its upper end in operative engagement with the opposite end of the valve rocker 9 from that to which the pushcylinder for the inner cup 23 which operates as a plunger therein, and between the bottom or closed ends of the two cups is a pressure chamber 26 in which oil is trapped to form a thrust transmitting oil cushion during each lifting stroke of the cam 4. The lower end of this pressure.

chamber is in the form of a well 27 in which is disposed a helical compression spring 28 tending to urge the inner cup outwardly of the outer cup. The interior of the inner cup constitutes a reservoir 29 for oil to be supplied as needed to maintain the pressure chamber 26 filled atall times, flow of oil into the pressure chamber being permitted through a passage 31 in the closed end of the inner cup. Controlling this fiow of oil and preventing its flow in the opposite direction is a check valve shown in the form of a ball 32 which is arranged to seat on the lower end of the passage 31 and has freedom to move oh? its seat to the limited extent permitted by the valve cage 33 which is held against the bottom end of the inner cup by the spring 28. The cage 33 is shown in the form of a cup whose bottom end is provided with one or more openings 34 which place the interior of the cage in communication with the pressure chamber exteriorly thereof. The upper ends of the pressure chamber 26 is enlarged as shown to form a shoulder 36 which serves as a positive stop for the lower end of the inner cup 23, and the side walls of this enlarged upper portion of the pressure chamber are radially spaced from and extend above the lower end of the inner cup.

Above the pressure chamber 26, the internal periphery of the outer cup is formed with longitudinally spaced apart lands 37 and 38. The innermost land 37 is of a slightly smaller diameter than the outermost land 38 and forms the bore in which the inner cup 23 Patented Oct. 16, 1956 is slidably fitted. Separating the lands 37 and 38 is an annular internal groove 39 which serves as an oil receiving chamber and is connected with an annular external groove 41 about the outer cup by a port 42. The external groove 41 is of suflicient width to maintain communication with a port 43 connecting the lifter guiding bore 2 with an oil gallery 44 provided in the crankcase which in turn is fed from the engine oil {lubricating system. Oil supplied via the gallery 44, port 43, groove 41, port 42, and groove 39 reaches the interior of the inner cup 23 through a port 45 extending through the side wall of the inner cup adjacent its upper or open end.

The upper or open end of the inner cup 23 is provided with a reduced external diameter portion 46 which extends into the receiving chamber formed by the groove 39 and has its upper end in laterally sliding abutment with the lower end of a closure member 47. This member 47 has its cylindrical external periphery slidably fitting the outermost land 38 of the outer cup and serves to transmit thrust between the inner cup and the lower end of the push rod 7. Above the land 38 and spaced from the upper end of the closure member 47 is a removable abutment 48 shown in the form of a removable out-springing snap ring engaging an annular groove in the internal periphery of the outer cup. This snap ring serves to limit outward movement of the closure member 47 and inner cup 23 under the biasing action of the spring 28 when the lifter assembly is removed from the engine.

The cylindrical external surface of the inner cup below the reduced diameter section 46 is of such length that its upper and lower ends 51 and 52 terminate inwardly of the outer cup from the upper and lower ends respectively of the innermost land 37 in all normal operating positions of the inner cup. Likewise, the upper and lower ends 53 and 54 of the cylindrical surface of the closure member 47 terminate inwardly of the upper and lower ends respectively of the outermost land 38. As a result, any accumulations of varnish or like deposits on the relatively sliding surfaces of the inner cup 23, outer member 24 and closure member 47 are prevented from interfering with movement of the inner cup and closure members inwardly of the outer cup during operation. This is an important feature of my invention, since any such interference as might otherwise occur could result in the lifter preventing full closure of the engine valve 13, with consequent burning of that valve and loss of engine power.

Also, by reason of the inner cup 23 slidably fitting the innermost land 37 and the closure member 47 receiving its lateral support directly from the outermost land 38 on the outer cup, all tendency of side thrust being transmitted from the closure member to the inner cup is avoided, and wear of the inner cup on the innermost land 37 is thus eliminated.

In addition, the design has the important advantage of reducing the cost of manufacture since only the innermost land 37 need be honed to the close tolerances required for proper fit of the inner cup, and this close limit honing operation is facilitated by the fact that the outermost land is bored to a larger diameter.

While only a single preferred embodiment of the invention has been disclosed, it is appreciated that numerous minor changes in the construction and arrangement of the parts may be made without departing from the spirit and scope of the invention as defined in the following claims.

I claim:

1. In a hydraulic lash take-up device, a reciprocable outer cup-shaped member having longitudinally spacedapart cylindrical lands on the internal surface of its side walls, means for guiding reciprocating movements of said outer member and for conducting hydraulic fluid thereto including a bore slidably fitting said outer member and a fluid supply passage having its terminus in said bore intermediate the ends of said outer member, said outer member having a port extending through its side wall and providing fluid communication between said passage terminus in all operative positions of said outer member and the internal surface of the outer member between said lands, an inner cup-shaped member having side walls formed with a cylindrical external surface slidably fitting the innermost of said lands and terminating at its end nearest the open end of said outer member with a reduced diameter portion, said inner member having a port extending through its side wall intermediate the ends of said reduced diameter portion, and a third member slidably abutting the outermost end of said portion and slidably fitting the outermost of said lands for transmitting thrust to and from said inner member during reciprocation of the outer member.

2. The invention defined by claim 1, wherein said cylindrical external surface has its innermost and outermost ends terminating inwardly of the outer memberfrom the respective innermost and outermost ends of said innermost land during normal operation of the device.

3. The invention defined by claim 2, wherein all surfaces of said third member slidably fitting said outermost land terminate in the direction outwardly of the outer member below the outermost end of said outermost land and extend inwardly of the outer member below the innermost end of said outermost land.

4. In a hydraulic lash take-up device, a pair of inner and outer cup-shaped members in nesting relation and having their closed ends spaced apart to define a hydraulic fluid pressure chamber, said outer member having longitudinally spaced-apart cylindrical lands on the internal surface of its side walls, said inner member having its side walls formed with a cylindrical external surface slidably fitting the innermost of said land and terminating within said pressure chamber, said cylindrical external surface being relieved by a section of reduced external diameter extending a distance inwardly of the outermost end of said innermost land from the open end of the inner member to form a receiving chamber for hydraulic fluid leaking between said members from said pressure chamber, said reduced diameter section having a port connecting the interior of the inner member with said receiving chamber, a check valve controlled passage in the closed end of said inner member accommodating one-way flow of hydraulic fluid from the interior of the inner member to said pressure chamber, a member in thrust transmitting relation with and forming a closure for the open end of said inner member, said thrust transmitting member having its innermost end in slidable abutment with the open end of said inner member and having a cylindrical external surface slidably fitting the outermost of said lands, and means for introducing hydraulic fluid to the interior of said inner member from a source externally of all three said members including a port in one of said outer and thrust transmitting members.

5. The invention defined by claim 4, wherein said innermost land is of smaller diameter than the outermost land and said cylindrical external surface of said thrust transmitting member extends into said receiving chamber and has its outermost end terminating inwardly of the outermost end of said outermost land.

References Cited in the file of this patent UNITED STATES PATENTS 2,109,815 Best Mar. 1, 1938 2,203,952 Eshbaugh June 11, 1940 2,665,669 Ellis Jan. 12, 1954 

